Monster Crocodiles, Part 2: Primeval

The
reason why crocodiles are more dangerous than sharks is that we are much more
likely to meet them, and when we do, the crocodile is more likely to see us as
prey than the shark.

According
to many shark experts, these fish bite people for a variety of reasons but many
attacks seem triggered by curiosity rather than actual predatory urges. Sharks
lack hands and fingers to examine new, unknown objects. They often explore
things by biting them. This is why, even if a great white shark does not
necessarily want to kill a human being, an innocent exploratory bite can spell
doom for its victim.

Crocodiles,
on the other hand, have always seen us as prey. Unlike sharks, they coexisted
with us from the very beginning. When our primate ancestors abandoned the
jungle and became savannah-dwellers, crocodiles of immense size populated
rivers. The fossilized remains of one of these crocodiles were found recently
in Tanzania.

They came
from a monster up to 7.5 meters long- larger than the largest Nile or Saltwater
crocodiles recorded for our times. The beast had a huge, heavy skull adorned
with a pair of crests or "horns" which revealed it to be a different
species from today's Nile crocodile. Scientists named it Crocodylus
anthropophagus, the "man-eating crocodile", as bite marks that
matched its teeth perfectly had been found in the bones of our hominin
ancestors. An even larger species, Crocodylus
thorbjarnarsoni, lived at about the same time in Kenya. This one was 8.2
meters long, or as the press put it, “big enough to star in Lake Placid”.

Because
crocodiles lived in rivers, which were vital to the survival of humans, there
was simply no way of escaping them. Other predators, like big cats, wolves and
hyenas, could be frightened with fire and other weapons. Crocodiles were
different. Like sharks in horror movies, they waited under the surface,
invisible, and attacked by surprise; and once they had you in their clutches, they
were simply too powerful to be fought.

Even the
arrival of civilization couldn´t stop crocodile attacks. In Ancient Egypt, land
predators such as lions and leopards were slowly exterminated, and attacks
became a rarity. Crocodiles, on the other hand, were an ever present threat
along the edges of the Nile. The Egyptians even had a special god, the
crocodile-headed Sobek, to protect them from the voracious reptiles. There's
even a legend from more recent times about an archaeologist in Egypt who found
a statue of Sobek by the river; removing it, however, was a mistake, as
crocodile attacks became incredibly frequent, and eventually, he was forced to
put Sobek back in his place; only then did the attacks stop.

To the
Greeks and other Europeans, the crocodile was a most fascinating beast. Absent
in Europe, it was therefore little understood, and in Medieval bestiaries, it
is often shown with a wolf or lion-like appearance, sometimes with spikes on
its back, and more often than not, weeping over the body of a human victim. For
according to many authors of the time, "if the crocodile findeth a man by
the brim of the water or by the cliff, he slayeth him if he may, and then he
weepeth upon him, and swalloweth him at the last".

This
tendency to shed tears during a meal eventually would make the crocodile a
symbol of hypocrisy, of false remorse. The expression "crocodile
tears" is a legacy of this legend, which has indeed a real life basis.
Crocodiles do shed tears while feeding. But these are not tears of remorse,
false or otherwise. It is simply the crocodile's way of keeping its eyes moist
while out of the water, for it cannot swallow under the surface, and its eyes
easily dry out in the air.

In Roman
times, crocodiles were sometimes seen at the Coliseum. The amphitheater was
flooded and epic naval battles were recreated. Crocodiles were released into
the water to devour any hapless gladiator or slave that fell from the ships.

Other
than this, however, the crocodile remained more or less a fantastic animal in
Europe for a long time. Unable to survive for long in cold climate, the
crocodile was restricted to tropical regions. But wherever it was found, it was
a constant danger along waterways, a dreaded and often revered force of nature.

To the
Aztec and many other Mesoamerican cultures, the Universe itself rested on the
back of a gigantic crocodile-like beast. The souls of the departed had to face
a terrible crocodile god during their journey towards Paradise.

But
although modern day crocodiles are big, scary and deadly enough to inspire
legends, nightmares and B movies, the truth is we only have to deal with a
shadow of what was once a frightening menagerie of monster crocodilians.

We often
think of crocodiles as "living fossils"; many people, including
crocodile experts, will tell you that they haven´t changed much in millions of
years.

This is
only half true. The basic design of all modern crocodiles- the low body, short
legs, long flattened tail and deadly jaws that make them such perfect ambush
predators- has indeed existed for millions of years. It has even been
"used" by non-crocodilian predators, including early whales and gigantic
amphibians from pre-dinosaur times.

But
crocodiles themselves are of rather recent origins, and they are only one of
many branches of crocodylomorphs, as scientists call them. Some of these
branches were truly the stuff of nightmares.

***

Like
their cousins the dinosaurs, crocodylomorphs started out small. The first ones
appeared in the Late Triassic, over 200 million years ago, and they coexisted
with the very first dinosaurs.

They were
small, agile and completely land-based. Rivers were already occupied by other
sorts of predators—giant amphibians resembling large-headed salamanders, and
the fearsome phytosaurs, which looked quite a lot like crocodiles themselves.
Crocodylomorphs would have to wait until these rivals disappeared to fill the
niche of the freshwater predator themselves. Meanwhile, they diversified into
plenty of different and often bizarre breeds.

This
diversification became most extreme during the Jurassic period. To avoid
competition with dinosaurs, many became aquatic. The most extraordinary ones
were the sea crocodiles.

Today,
the saltwater crocodile often lives in coastal waters and may even swim long
distances from island to island. They have been seen fighting- and devouring-
sharks in the sea. But they are still amphibious animals, and must return to
land to rest and to lay their eggs.

The sea
crocodiles of the Jurassic were different. They became so well adapted to the
ocean that if one of them appeared today, we would probably mistake it for some
sort of bizarre mutation- a cross between a crocodile and a fish. Many of them
lost their body armor; their webbed feet turned into actual flippers, and their
tails turned into caudal fins, very reminiscent of a shark's.

They
probably gave birth to live young, like many other sea reptiles of the time.
Free from the need of returning to land, they spent their lives in open waters.
Many, like Metriorhynchus, had long, slender snouts that would resemble
some living crocodilians, like the gharial; they were superbly adapted to
capture fish. Usually, they measured about three meters long-- smallish compared
to our largest crocodiles-- but they were far better swimmers.

Dakosaurus vs. the predatory marine reptiles known as Eurhinosaurs

Not all
of them were fish eaters, however. In 1987, the remains of an unusual (well, especially
unusual) four or five meter long sea crocodile were found in Argentina.
Instead of a long gharial-like snout, it had a short and deep skull, very reminiscent
of a carnivorous dinosaur's. The scientists nicknamed it Godzilla for this
reason.

A later
study found that this sea crocodile, formally known as Dakosaurus, could
slice its prey into smaller chunks with its large, blade-like serrated teeth.
This is completely different to the teeth of modern crocodiles which are
conical and blunt, meant to pierce and hold but completely unable to slice.

Indeed, Dakosaurus
was a crocodile turned by evolution into the Jurassic equivalent of a great
white shark. It didn´t chase after small fish like its cousins; it went for the
giant ichthyosaurs and plesiosaurs of the time, even those larger than itself,
and bit off huge chunks of their flesh, killing them via blood loss. With
monsters like Dakosaurus roaming the seas, it is little wonder that, to
our knowledge, no dinosaurs ever managed to conquer the Jurassic oceans.

Machimosaurus attacks Dakosaurus, to the alarm of a dinosaur called Eustreptospondylus

As if Dakosaurus
wasn´t scary enough, the Jurassic sea would give rise to even larger
crocodylomorphs. The largest we know of was Machimosaurus, found in
Europe in 1837. Unlike Dakosaurus, it had a crocodile-like body and
blunt, conical crocodile teeth. However, it was big enough to make a meal out
of Dakosaurus- at least 9 meters long, making it not only the largest of
its kind, but also one of the top predators of its days.

Although
its snout was long and slender, there's good evidence that Machimosaurus, being
so large, could feed on anything it wanted and not just fish. Its bite marks
have been found in the fossilized shells of sea turtles and even in the bones
of a giant long-necked dinosaur.

Scientists
believe Machimosaurus swam long distances in the open sea, but probably
hunted near coasts, snatching any unfortunate animal that got too close.

Machimosaurus was only the first in a long line of crocodylomorphs
(from different families) that achieved monstrous sizes.

During
the Cretaceous, both dinosaurs and crocs would reach their greatest diversity.
The largest carnivorous dinosaurs, such as Spinosaurus, Carcharodontosaurus,
Giganotosaurus and of course, the iconic Tyrannosaurus rex were all
from the Cretaceous. The biggest of them all, Spinosaurus, could weigh
up to 9 tons. But the largest Cretaceous crocodiles dwarfed even this monster.

Sarcosuchus puts a dinosaur to flight

In 1966,
two paleontologists named a new species of Cretaceous crocodile as Sarcosuchus
imperator, the flesh-eating emperor croc. Despite its awesome name, this
beast remained obscure until 1997, when American paleontologist Paul Sereno
found additional remains in Niger.

These new
finds were widely publicized and Sarcosuchus finally became famous under
the nickname of Super Croc. It was its monstrous size that captured the
public's imagination; at 12 meters long, with an almost 2 meter skull and
probably up to 10 tons, it was claimed to be the largest crocodile of all
times.

Sarcosuchus coexisted with large carnivorous dinosaurs such as Suchomimus,
but the general consensus is that it was the dinosaurs, rather than the
crocodile, who were in constant danger of being eaten. After all, dinosaurs had
to drink, and an adult Sarcosuchus was too big to survive solely on
fish.

As if
this wasn´t bad enough for the hapless dinosaurs, they had another crocodilian
enemy on land.

The
remains of this creature were also found by Paul Sereno, and described in 2009.
It was obviously a crocodile, but unlike any other crocodile ever found. It had
a pair of horn-like crests on its head, and some of its teeth jutted out of the
mouth like enormous tusks. The creature received the nickname of Boar Croc, and
was described as "a sabertooth tiger clad on armor". It was not a
water-based ambush hunter. It was a land-dwelling predator able to walk and run
at high speed, and its enormous teeth were probably an adaptation to deal with
large, thick skinned prey; a six meter long dinosaur hunter.

5 comments:

Should have mentioned that when the teeth of sebecids were first found in South America, paleontologists thought they were evidence of late survival of giant carnivorous dinosaurs into after the Cretaceous.

I am guilty of it myself- I went out fossil hunting one day and found many small pieces of what I took to be turtle shells. Imagine my surprise when I did some research and found that they were actually bits of a glyptodont's shell- basically an armadillo the size of a Volkswagen beetle.

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